Updated IsDroidInRange routine to correctly calculate whether a droid is in range

The routine would falsely report that two droids were in range of each other if the difference in their Y coordinates were less than the droid's range.

So one droid at `[10, 5]` and another at `[1, 5]` both with a range of `2` would be reported to be in range of each other their two Y values are less than the droid's range.